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Comparative Cell Biology in Diplomonads

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Comparative Cell Biology in Diplomonads Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1303 Comparative Cell Biology in Diplomonads ELIN EINARSSON ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-554-9374-5 UPPSALA urn:nbn:se:uu:diva-264541 2015 Dissertation presented at Uppsala University to be publicly examined in A1:111a, BMC, Husargatan 3, Uppsala, Friday, 4 December 2015 at 09:15 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Professor Scott Dawson (UC Davies, USA). Abstract Einarsson, E. 2015. Comparative Cell Biology in Diplomonads. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1303. 84 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9374-5. The diplomonads are a diverse group of eukaryotic flagellates found in microaerophilic and anaerobic environments. The most studied diplomonad is the intestinal parasite Giardia intestinalis, which infects a variety of mammals and cause diarrheal disease. Less is known about Spironucleus salmonicida, a parasite of salmonid fish, known to cause systemic infections with high mortality. We created a transfection system for S. salmonicida to study cellular functions and virulence in detail (Paper I). The system was applied to explore the mitochondrion-related organelle (MRO) in S. salmonicida. We showed that S. salmonicida possesses a hydrogenosome (Paper II) with a higher metabolic capacity than the corresponding MRO of Giardia, the mitosome. Evolutionary analysis of key hydrogenosomal proteins showed ancient origin, indicating their presence in the ancestral diplomonad and subsequent loss in Giardia. Annexins are of evolutionary interest since these proteins are found across all kingdoms. Annexin-like proteins are intriguingly expanded into multigene families in Giardia and Spironucleus. The annexins of S. salmonicida were characterized (Paper III) with distinct localizations to various cellular structures, including a putative adhesion structure anterior in the cell. The disease-causing Giardia trophozoites differentiate into infectious cysts, a process essential for transmission and virulence of the parasite. Cysts are often spread via contaminated water and exposed to environmental stressors, such as UV irradiation. We studied the survival and transcriptional response to this stress factor (Paper IV) and results showed the importance of active DNA replication machinery for parasite survival after DNA damage. In addition, we studied transcriptional changes along the trajectory of encystation (Paper V), which revealed a coordinated cascade of gene regulation. This was observed for the entire transcriptome as well as putative regulators. Large transcriptional changes appeared late in the process with the majority of differentially regulated genes encoding hypothetical proteins. We studied the localizations of several of these to gain information of their possible function. To conclude, the diplomonads are complex eukaryotic microbes with cellular processes adjusted to match their life styles. The work in this thesis has provided insight of their adaptations, differences and similarities, but also new interesting leads for future studies of diplomonad biology and virulence. Keywords: Giardia intestinalis, Spironucleus salmonicida, intestinal parasite, hydrogenosome, encystation, gene regulation, transfection, diplomonad, antigenic variation, annexin Elin Einarsson, Department of Cell and Molecular Biology, Box 596, Uppsala University, SE-75124 Uppsala, Sweden. © Elin Einarsson 2015 ISSN 1651-6214 ISBN 978-91-554-9374-5 urn:nbn:se:uu:diva-264541 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-264541) In nature nothing exists alone - Rachel Carson Till min farmor Signe Cover photos by Stan Erlandsen and Andrew Hemphill List of Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I Jerlström-Hultqvist J, Einarsson E, Svärd SG. (2012) Stable transfection of the diplomonad parasite Spironucleus salm- onicida. Eukaryotic Cell. 11(11):1353–61 II Jerlström-Hultqvist J, Einarsson E, Xu F, Hjort K, Ek B, Stein- hauf D, Bergqvist J, Andersson JO, Svärd SG. (2013) Hy- drogenosomes in the diplomonad Spironucleus salmonicida. Nature Communications. 4:2493 III Einarsson E, Ástvaldsson Á, Hultenby K, Andersson JO, Svärd SG, Jerlström-Hultqvist J. Comparative Cell Biology and Evo- lution of Annexins in Diplomonads. Submitted manuscript. IV Einarsson E, Svärd SG, Troell K. (2015) UV irradiation re- sponses in Giardia intestinalis. Experimental parasitology. 154:25-32 V Einarsson E, Troell K, Höppner, M, Grabherr M, Ribacke U, Svärd SG. Coordinated Changes in Gene Expression Through- out Encystation of Giardia intestinalis. Submitted manuscript. Reprints were made with permission from the respective publishers. Publications not included in the thesis. I Franzén O, Jerlström-Hultqvist J, Einarsson E, Ankarklev J, Ferella M, Andersson B, Svärd SG. (2013) Transcriptome pro- filing of Giardia intestinalis using strand-specific RNA seq. PLoS Computational Biology. 9(3):e1003000 II Xu F, Jerlström-Hultqvist J, Einarsson E, Ástvaldsson Á, Svärd SG, Andersson JO. (2014). The genome of Spironucleus salmonicida highlights a fish pathogen adapted to fluctuating environments. PLoS Genetics. 10(2):e1004053. III Einarsson E, Svärd SG. (2015). Encystation of Giardia intesti- nalis- a journey from the duodenum to the colon. Current Tropical Medicine Reports. 2(3):101-109. Review article. Contents Introduction ................................................................................................... 11 Diplomonads ............................................................................................ 11 The Giardia cell ....................................................................................... 14 Giardia classification ............................................................................... 15 The life cycle of Giardia .......................................................................... 16 The trophozoite .................................................................................... 17 Energy metabolism ................................................................................... 23 Differentiation .......................................................................................... 24 Giardia pathogenesis ................................................................................ 31 Antigenic variation ................................................................................... 34 Genomics and transcriptomics ................................................................. 38 Spironucleus ............................................................................................. 40 Infection and transmission ....................................................................... 41 Genomics and transcriptomics of S. salmonicida ..................................... 42 Metabolism ............................................................................................... 43 Cell biology .............................................................................................. 44 Present Investigation ..................................................................................... 46 Aim of the thesis .................................................................................. 46 Establishment of S. salmonicida as a diplomonad model system (Paper I) ............................................................................................... 46 S. salmonicida possess hydrogenosomes (Paper II) ............................ 48 Annexin diversity revealed in S. salmonicida (Paper III) .................... 50 UV stress in G. intestinalis (Paper IV) ................................................ 53 The differentiation of G. intestinalis is a coordinated cascade of gene regulation (Paper V) .................................................................... 54 Conclusions and future perspectives ............................................................. 58 S. salmonicida can be used as a biological model system ................... 58 Can S. salmonicida form cysts? ........................................................... 58 Hydrogenosomes: one organelle, several functions ............................ 59 S. salmonicida have an attachment organelle ...................................... 59 Giardia cysts- masters of survival ....................................................... 60 What dictates differentiation in Giardia intestinalis? .......................... 60 Pieces missing in the differentiation puzzle ........................................ 60 VSP switch event during encystation .................................................. 61 What controls the antigenic switch? .................................................... 61 Is antigenic variation a common trait of diplomonad parasites? ......... 62 Sammanfattning på svenska (Summary in Swedish) .................................... 63 Acknowledgements ....................................................................................... 66 References ..................................................................................................... 70 Abbreviations ADI Arginine deiminase AP Adaptor protein ASH Allelic sequence heterozygosity CLO Carpediemonas-like organism COP Coat protein Cpn60 Chaperonin 60 CRMP Cysteine-rich membrane protein CRP Cysteine-rich
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